1. Field
Example embodiments relate to a high-electron mobility transistor (HEMT) and/or a method of manufacturing the same and, more particularly, to a HEMT having normally-off characteristics and/or a method of manufacturing the same.
A. 2. Description of the Related Art
In a power conversion system, an efficiency of a power switching device may affect the efficiency of the entire system. Although a power metal oxide semiconductor field effect transistor (power MOSFET) using silicon or an insulated gate bipolar transistor (IGBT) have mostly been used as a switching device, there is a technical limit to increasing the efficiency of the switching device due to the material limitations of silicon itself.
Research has been conducted into a high-electron mobility transistor (hereinafter, HEMT).
A HEMT may include semiconductor layers having different electrical polarization characteristics. In a HEMT, a semiconductor layer having a relatively high polarizability may cause a 2-dimensional electron gas (hereinafter, 2DEG) in another semiconductor layer that form a heterojunction with the semiconductor layer having the relatively high polarizability. The 2DEG may be used as a channel between drain and source electrodes, and a current flowing through the channel may be controlled by a bias voltage applied to a gate electrode.
A HEMT using a heterojunction formed of a Group III nitride semiconductor may have normally-on characteristics. To turn off the HEMT having the normally-on characteristics, a minus power source may apply a negative (−) bias voltage to the gate electrode, and an additional circuit may be used to reduce (and/or prevent) the flow of an overcurrent during the application of power.